Hi, guys. I had several questions about DRBD that should hopefully be easy
to answer. For background, I'm bringing up a new system with a pair of
identical servers. I intend to failover a RAID-0 array created from 12 SCSI
drives. The drives are configured as one big array and the entire thing
will be replicated. I'd prefer to use the 2.6 kernel and I'm currently
testing using 0.7 development releases of DRBD.
- Since I'm failing over the entire /dev/md1 array, do I need to specify a
disk-size in my drbd.conf? I intend to put the metadata on the array as
well. The filesystem will be added after the DRBD device is up (in other
words, mkreiserfs /dev/nb0). So, I think I want the reiserfs filesystem to
take up most of the md1 device and the metadata to take up the rest. Does
this happen automatically if I just say to put the metadata on that same
device and don't specify a disk-size?
- I rebooted the primary to test a failover. The system failed over to the
secondary just fine. When the primary came up and the units started to
sync, I got a kernel panic due to a Reiserfs journal-601 error that said it
was trying to write past the end of the device. I meant to save the actual
numbers, but it wasn't even close. It said the size was something like
400000 and it was trying to write to 1500000. Could that be caused by a
lack of the disk-size? I was running the 20040528 snapshot at the time but
have since updated to the recent release candidate 1. In my testing, the
system usually fails over fine and rebuilds. It was just this one time I
saw an error.
- The drives being failed over are a RAID-0 array. If a drive fails, I'll
be replacing it. This means that a bunch of data out of the middle of the
array goes away. When I bring that machine back online, I can't just write
the data that the primary has received while it has been offline, I need to
write all that data plus everything that was on the now-replaced drive.
Will DRBD handle this automatically? Will I need to force a full resync
somehow?
- Pretty much the same question, but involving the metadata. If I replace a
drive that includes some or all of the DRBD metadata, will I still be able
to bring up the device when the system is restarted? Will DRBD realize the
metadata is missing or corrupted and rebuild it?
Thanks, guys, for the help.
Jeff
--
jeff at jltnet.com